PROJECT SUMMARY/ ABSTRACT: Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency of newborns, and affects 7% of patients admitted to a neonatal intensive care unit. Despite years of research there is a gap in the understanding of the underlying pathophysiology of disease, and a lack of novel therapeutic approaches. Rho kinases (ROCK) are serine/ threonine kinases and are involved in multiple cellular processes including regulating tight junction function, actin cytoskeleton contraction, inflammatory cytokines and cell death. We and others, have previously demonstrated the relevance of these pathways to the pathophysiology of NEC. The objectives of this R03 proposal are to define mechanism(s) of ROCK activation, identify molecular pathways targeted by ROCK during experimental NEC and to determine the mechanisms by which ROCK inhibition limits NEC progression. The central hypothesis is that oxidative stress and LPS induce ROCK activation, resulting in cytoskeletal contraction and tight junction degradation that enhances mucosal and systemic inflammation and epithelial apoptosis. If this hypothesis is correct then ROCK inhibition will be protective against these effects and NEC. To test this hypothesis, we will examine the effects of signaling through ROCK pathway on tight junction proteins, epithelial permeability, inflammation and apoptosis during experimental NEC. The objective of this application is to define the ROCK-mediated molecular interactions that direct epithelial function during NEC. These studies will have great power since they will be performed in vitro, in enteroids, and in vivo models of NEC as well as in human intestinal samples from infants with and without NEC. We will determine whether inhibition of the ROCK pathway (by pharmacological and genetic approaches) can stabilize tight junctions and minimize inflammation, decrease cell death, and influence the outcomes and survival in experimental NEC. These findings will build upon my current studies, and have a significant positive impact on human health by providing a new understanding of the mechanisms governing epithelial intestinal barrier function during NEC.